1. Field of the Invention
This invention relates generally to temperature measurement devices, specifically to in-line thermometers for fluid temperature measurement.
2. Discussion of Prior Art
It is well known in the art to utilize various types of thermometers for measuring fluid temperatures. Such thermometers are typically mercury or alcohol bulb type, bi-metal type, thermocouple, RTD etc. All aforementioned thermometers require the temperature sensing element to be in intimate contact with the fluid or in thermal communication through a “well”. As a result, numerous fittings must be assembled or welded into the fluid carrying plumbing to accommodate this need. These fittings are not only costly to assemble and procure, they are prone to leaks and unsanitary and corrosive conditions in food, pharmaceutical, petrochemical, and similar applications. These leaks can be dangerous and unhealthy. In cases where portability of the instrument is important, these type thermometers are difficult and time consuming to remove and plug the vacated holes. It is also well known in the art to install a surface type thermometer to the fluid carrying member such as a liquid crystal thermometer or surface type RTD or thermocouple. Such examples are prior art U.S. Pat. No. 5,415,203 by Huang and U.S. Pat. No. 5,634,426 by Tomlinson, where a liquid crystal thermometer is applied directly to the fluid carrying member, a pipe. In the case of the liquid crystal thermometer, it is not practical to remove it after the temperature reading is made without permanently damaging the unit due to the adhesive used to apply the thermometer. As such, portability and re-use is impossible. In the case of surface type RTD's or thermocouples, installation requires the application of messy adhesives, thermal coupling fluids and tapes. In addition, a remote read-out device must be used to take the measurement. Although cumbersome, the elements can typically be reused.